Pest Management Options: Organic Considerations

Organic Certification

The Organic Foods Protection Act of 1990 required the United States Department of Agriculture (USDA) to develop uniform national organic standards. From this legislation, arose the National Organic Program (NOP), which through a 15-member National Organic Standards Board (NOSB) developed regulatory codes that must be followed for selling any products labeled as organic. Since 2002, all organic farming and processing operations are certified by a USDA Accredited Certification Agency (ACA) to assure consumers that all NOP regulations are being followed. The NOP maintains a list of ACAs on their website (www.ams.usda.gov/NOP). The choice of certifiers is often dictated by cost, experience with the crops being produced, and familiarity with the targeted marketing outlets. Organic producers with gross sales less than $5,000 per year do not need to be certified, but they do need to follow all NOP regulations in order to use the organic label.

The USDA defines organic as a labeling term that refers to an agricultural commodity produced in accordance with the NOP. In other words, the USDA views the term organic primarily as a marketing category. However, in order to access the organic market, the USDA specifically states that an organic production system must be managed to respond to site-specific conditions by integrating cultural, biological, and mechanical practices that foster the cycling of resources,promote ecological balance, and conserve biodiversity.

Soil, nutrient, pest, and weed management are all interrelated on organic farms and must be managed in concert for success. Accredited Certification Agencies should be able to provide a template for the Organic System Plan (OSP). Additionally, the National Sustainable Agriculture Information Service, (formerly ATTRA), has produced a guide to organic certification that includes templates for developing an OSP (attra.ncat.org/organic.html).

Under NOP Section 205.202, “any field or farm parcel from which harvested crops are intended to be sold, labeled, or represented as “organic,” must have had no prohibited substances, as listed in §205.105, applied to it for a period of three years immediately preceding harvest of the crop.” This three-year period is referred to as the transition period. During this time, growers will likely assume greater operating expenses, without earning organic price premiums.

Organic Orchard Design

Orchard design and cultivar selection have a long term impact on pest control. While apple trees are resilient and can usually survive for decades without human intervention, year-round migration of pests from wild or unmanaged apple trees almost guarantee pest damage to unsprayed fruit. Surveys have shown that more than 95% of the fruit on wildor abandoned apple trees are usually damaged or infested.

Some specific organic pest control methods are more effective when there are fewer orchard edges bordering natural areas or unmanaged orchards. For example, pheromone mating disruption is much less effective in apple orchards where mated female codling moths, oriental fruit moths, or apple maggots can easily fly into the orchard from surrounding areas. In some situations, growers may want to selectively remove unmanaged trees that are closely related or a host for other pests of the fruit crop.

For example apple pests may move from crabapple trees, hawthorns, cedar, juniper, mountain ash, cotoneaster, and quince. To minimize migration of pests, these species would need to be removed within a minimum of a half-mile of the orchard.

Edge habitats can be beneficial for wildlife biodiversity by providing habitat for beneficial insects. They also act as a tool in resistance management of key insect pests, such as codling moth, peach twig borer, or western cherry fruit fly as wild-type individuals from surrounding habitat migrate into your orchard and mate with the resident pest population. Having these two gene pools intermix will help delay the development of pesticide resistance pesticides.

Pest Managment Concerns

Beneficial insects are an excellent tool in an organic production program but cannot be counted on as a stand-alone method of control. Any pest management program needs to be a multi-faceted plan of action. A well balanced “toolbox” for an organic pest management program may include beneficial insects, bat boxes, insect-specific bacteria or viruses,mating disruption, tangle foot, apple bags, baits, traps, and less toxic organic pesticides.

Vertebrate pests such as mice and voles can become a serious problem in orchards during the winter where surrounding hedgerows, brambles, or fields provide an ideal rodent habitat during the summer months. When snow cover deprives them of other food sources, they tend to gnaw on the lower branches and the crown of trees, which can cause damage or even death. Many species of fruit-eating birds also thrive in hedgerows or woods, and fruit damage by birds in late summer tends to be more problematic where they have an ideal habitat around orchards.

Replanting certain fruit trees into land previously planted with fruit trees often results in stunted trees and reduced yields. This disease syndrome, known as replant disease, has nonspecific causes that often differ from one site to another. Multiple biotic and abiotic factors are involved in replant disease. Organic growers can potentially minimize the negative effects of apple replant disease by avoiding the old tree rows of the previous orchard when planting new trees. Additionally, several rootstock selections are more resistant to replant disease.

Pre-planting cover crops of marigold flowers, certain oilseed rape cultivars, and Sudan grass hybrids, may provide partial control of replant disease in some orchards. Replacing soil from the planting hole with a mixture of fresh soil and compost may also be helpful. Other factors that may alleviate apple replant disease include allowing a fallow period before planting, soil pH adjustment, minimizing soil compaction, improving soil drainage, correcting nutrient deficiencies, and providing supplemental irrigation immediately after nursery trees are planted in the orchard.